• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.587-595
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• 2000

The most problems of domestic sewage for BNR(Biological Nutrients Removal) process are deficiency of carbon source and low C/N ratio. Primary sludge fermentation is seemed to be one of the best solutions producing biodegradable organic substrates. Soluble organic materials from sludge fermentation are mainly SCFAs(Short-Chain Fatty Acids) with 2~5 carbon atoms. In this research, it was attempted to apply $A_2/O$ process with the side-stream acid fermenter to improve the nutrients removal efficiency. The result showed that proper SCFAs production is about 3.000mg/L with SRT of 4~5 days. SCFAs yield of approximately 0.10~0.16 mg SCFAs(as COD) per mg of primary sludge(as COD) were achieved. The ratio of acetic. propionic. butyric and valerie acid were 1, 0.7, 0.5 and 0.6. Significant improvements of nutrients removal over 70% in BNR process were observed. thus will reduce the demand for chemical dosing to increase nutrients removal efficiency. When the fermentate was entered $A_2/O$ process, the ratio of phosphate release to substrate uptake amounts to $0.34gPO_4-Pg^{-1}COD$.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.588-596
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• 2006

The surface of polystyrene membrane treated by Ar, $O_2$ plasma, and the effects were observed before and after the treatment and permeability of $CO_2$, $N_2$ and selectivity of $CO_2$ relative to $N_2$ was measured using continuous flow gas permeation analyzer (GPA). The mole ratio of O over C in the surface was increased from 0 to 0.179 with Ar plasma treatment and route mean square of surface was increased from $15.86{\AA}$ to $71.64{\AA}$. Therefore the contact angle was decreased from $89.16^{\circ}$ to $18.1^{\circ}$. Thus Plasma treatments made surface of membrane tend to be highly hydrophilic. The optimum condition for the $CO_2$ permeability and ideal selectivity of the plasma treated membrane was as follows: the measurement of Ar (60 W, 2 min, $70^{\circ}C$) plasma treatment was $1.14{\times}10^{-12}[m^3(STP){\cdot}m/m^2{\cdot}sec{\cdot}atm]$ and 4.22. In the case of $O_2$ plasma treatment, the contact angle was decreased at $13.56^{\circ}$ with increase of O/C ratio ($0.189{\AA}$) and route mean square of surface ($57.10{\AA}$). The optimum condition for the $CO_2$ permeability and ideal selectivity of the plasma treated membrane was as follows: the measurement of $O_2$ (90 W, 2 min, $70^{\circ}C$) plasma treatment was $7.1{\times}10^{-12}[m^3(STP){\cdot}m/m^2{\cdot}sec{\cdot}atm]$ and 11.5. After plasma treatment, the changes of membrane surface were all subtly linked with both cross-linking and etching effects. Finally, it was confirmed that the gas permeation capacity and selectivity of the modified membrane with plasma could be improved by an appropriate control of the plasma conditions such as treatment time, the power input and sort of plasma gas.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.816-820
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• 2013

We investigated the characteristics of the silicon oxy-nitride and nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) at the low temperature with a varying $NH_3/N_2O$ mixing ratio and a fixed $SiH_4$ flow rate. The deposition temperature was held at $150^{\circ}C$ which was the temperature compatible with the plastic substrate. The composition and bonding structure of the nitride films were investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Nitrogen richness was confirmed with increasing optical band gap and increasing dielectric constant with the higher $NH_3$ fraction. The leakage current density of the nitride films with a high NH3 fraction decreased from $8{\times}10^{-9}$ to $9{\times}10^{-11}(A/cm^2$ at 1.5 MV/cm). This results showed that the films had improved electrical properties and could be acceptable as a gate insulator for thin film transistors by deposited with variable $NH_3/N_2O$ mixing ratio.

• Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.100-110
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• 2024

Biometric evaluation and reproductive biology of Oreochromis niloticus were studied from Geray Reservoir. Between November 2021 and August 2022, 316 O. niloticus specimens were collected from this reservoir. The observed male to female sex ratio was 1:1.14, which was statistically insignificant compared with the hypothetical 1:1 sex ratio (X² = 1.27, p > 0.05). The length-weight relationship was curvilinear with allometric growth (b < 3) and statistically significant from the expected isometric growth pattern (b = 3). The regression equation for females was TW = 0.0264TL^2.72 (r² = 0.90, n = 168), males (TW = 0.0183TL^2.79, r² = 0.93, n = 148), and combined sexes (TW = 0.0229TL^2.76, r² = 0.91, n = 316). Gonadosomatic index (GSI) ranged from 0.8 to 1.4 (males) and 1.8 to 4.9 (females). The breeding season lasted from March to June, with a GSI peak in April. Fecundity ranged from 279 to 1,528 eggs./fish, with a mean of 1,025 eggs./fish. The correlation between absolute fecundity and length was more significant (F = 0.76TL^2.8, R² = 0.94, p < 0.05) than with weight (F = 17.683TW^0.71, R² = 0.92, p < 0.05). This study provides basic information on the biology of O. niloticus in the Geray Reservoir for future fishery management tools for the conservation and utilization of this valuable freshwater fish.

• Journal of Animal Environmental Science
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• v.4 no.1
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• pp.47-53
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• 1998

The purpose of this study was to investigate the change of temperature, moisture content, weight and chemical properties in swine manure during the maturing process and moisture content of swine manure. The manure production on the early time(1 days), middle(25 days: and late(50 days) were made by moisture 45%, 55%, 65%, 75% in swine manure, according to manure treatment of the early time, the highest temperature of swine manure treatment was 59$^{\circ}C$ as moisture 75% after mixed 24 hours, the lowest 45% in mixed 25 days(middle time), 32$^{\circ}C$ as moisture 45% in mixed 50 days(late time). 2. Weight change during maturing manure, the most treatment of weight decrease was 17.4% as moisture 45%, the least of those was 12.2% as moisture 75% during maturing process of swine manure. 3. Volume change during maturing manure, the most treatment of volume decrease was 37.1% as moisture 65%, the least of those was 32.1% as moisture 55% during maturing swine manure, but not big difference between treatment. 4. T-N, P2O5, K2O content of compost were increased during maturing process, On the contrary, T-C content and C/N ratio were reduced.

• Journal of Animal Environmental Science
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• v.3 no.1
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• pp.13-18
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• 1997

This study was conducted to investigate the physicochemical changes during the aerobic composting of swine manure mixed with bulking agent, sawdust(v/v, 1:1), in a full-scale composting plant using rectangular escalator-aginated bed composting system. Physical and chemical properties were analyzed on the samples which were collected at 5, 15, and 25 day of composting, curing and final step. The results of this study were summarized as follows; 1. Moisture and K2O content, and pH of final step were higher than those of 5th day of composting (p＜0.05). 2. Ammonium nitrogen, total organic corbon and organic matter content, and electrical conductivity(EC) were significantly decreased (p＜0.05) but nitrate nitrogen, ash and P2O5 content increased(p＜0.05) throughout the aerobic composting process. 3. Total organic carbon per total nitrogen(C/N) and total organic matter per total nitrogen(OM/N) ratio were significantly decreased throughout the aerobic composting process(p＜0.05). 4. Physical and chemical properties of swine manure were varied by aerobic fermentation using rectangular escalor-aginated bed composting system.

• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.4
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• pp.99-108
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• 1982

This thesis aims to estimate the rainfall runoff from paddy field in a small watershed during irrigation period. When the data observed at the proposed site are not available, the Monthly Runoff Equation of Korean Rivers which was derived from data observed under the following assumptions is used to study the water balance. a. Monthly base flow was assumed as 10. 2mm even if these is no mouthly rainmfall. b. Monthly comsumption of rainfall was ranged from 100 to 2OOmm without relation to the rainfall depth. However, the small watershed which consists mainly of paddy fields encounters severe droughts and accordingly the baseflow is negligible. Under the circumstances the author has developed the following equation called "Flood Irrigation Method for Rainfall Runoff "taking account of the evapotranspiration, precipitation, seepage, less of transportation, etc. R= __ A 7000(1 +F) -5n(n+1)+ (n+1)(Pr-S-Et)] where: R: runoff (ha-m) A: catchment area (ha) F: coefficient of loss (o.o-0. 20) Pr: rainfall (mm) S: seepage Er: evapotranspiration (mm) To verify the above equation, the annual runoff ratio for 28 years was estimated using the Monthly Runoff Equation of Korean Rivers the Flood Irrigation Method and the Complex Hydrograph Method based on meteorological data observed in the Dae Eyeog project area, and comparison was made with data observed in the Han River basin. Consequently, the auther has concluded that the Flood Irrigation Method is more consi- stent with the Complex Hydrograph Method and data observed than the Monthly Runoff Equation of Korean Rivers.

• Applied Biological Chemistry
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• v.7
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• pp.39-43
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• 1966

This experiment was carried out to determine how the water soluble, the available phosphoric acid and the urea-N would change as time went by, when mixtures of calcium superphosphate and urea were made. Two kinds of materials, i. e., calcium superphosphate and urea were engaged in this experiment. Two kinds of mixed fertilizer, i. e., A and B were made up by mixing these materials to satisfy the following ratio. 1) Urea 1+ calcium superphosphate 1${\cdots}\;{\cdots}$A 2) Urea 1+ calcium superphosphate 2${\cdots}\;{\cdots}$B A and B pIaced placed in desiccators respectively a six-month period. During the time of storage, the water soluble, the available $P_2O_5$ and the urea-N were measured once a month, seven times with the control measurement. The results may be summarized as follows. 1. The urea-N in both A and B showed no change by the passage of time. This fact suggested that the mixing of calcium superphosphate with urea was not unfavourable. 2. A and B showed no diminishing in the water soluble and the available $P_2O_5$ in the process of time. This fact indicated that the combination of calcium superphosphate with urea was not unfeasible.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1855-1862
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• 2018

A reliable set of low-energy electron collision cross sections for the triethoxysilane (TRIES) molecule was derived based on the measured electron transport coefficients for a pure TRIES molecule by using an electron swarm method and a two-term approximation of the Boltzmann equation. The electron transport coefficients calculated using the derived set are in good agreement with experimental value over a wide range of E/N values (ratio of the electric field E to the neutral number density N). The present electron collision cross section set for the TRIES molecule, therefore, is the most reliable so far for plasma discharges and for materials processing using the TRIES molecule. Moreover, the electron transport coefficients for the TRIES-Ar and the $TRIES-O_2$ mixtures were also calculated and analyzed over a wide range of E/N for the first time.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.579-584
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• 2013

The study was conducted to investigate changes in the characteristics of inorganic components during fermenting process of organic liquid fertilizers according to the type and ratio of microorganism and the amount of molasses when producing organic liquid fertilizers using sesame oil cake and rice bran. To select appropriate microorganisms, liquid fertilizers were produced through a 90-day fermentation process by adding mag-ggeo-li, yogurt, dried yeast, and leaf mold. The pH in liquid fertilizer was decreased, and then increased in all microorganism samples except the mag-ggeo-li sample. The EC was rapidly increased in all samples until the $10^{th}$ days after production, and showed no changes after the $60^{th}$ days in dried yeast and after the $30^{th}$ days in the other samples. The concentration of $NH_4$-N was generally increased with time. The concentration of $P_2O_5$ was rapidly increased until the $10^{th}$ days after production and was maintained at about 1% regardless of the type of microorganism. In terms of the characteristics of liquid fertilizers according to the ratio of selected dried yeast, the pH was decreased until the $30^{th}$ days after producing the liquid fertilizers, and then was increased regardless of the ratio of dried yeast. The EC was increased with time and showed no differences depending on the amount of dried yeast. The concentration of $NH_4$-N was increased with time and in proportion to the amount of dried yeast. In terms of the characteristics of liquid fertilizers according to the ratio of molasses, the pH was decreased with increasing the molasses. The EC and concentration of $P_2O_5$ were no differences according to the amount of molasses. When 3% molasses was added, the content of $NH_4$-N was 2.6 mg $L^{-1}$ at the beginning and was at 3,025 mg $L^{-1}$ on the $90^{th}$ days.